Spring Boot Training Playground

Playground for the Spring Boot training.

Super simple 3 tier layer architecture Spring Boot application.

Including:

Repository layer
- Spring Data JPA
- MySQL
- Flyway (database migration)
Service layer
- Mapstruct to map object from the repository layer into a service layer object to not leak repository concerns into the other parts of the application.
Rest API layer
- Spring Web MVC

Prerequisites

Java 11
Docker (Desktop)

You don't need to have Maven installed. The project contains the Maven wrapper out of the box.

Build and run the project

./mvnw clean package

Start MySQL in a Docker container:

docker-compose up -d

Run the Spring Boot application using the Spring Boot Maven plugin.

./mvnw spring-boot:run

Exercises

Play around with Spring Profiles
- Introduce a profile like acceptance, production
- Experience how property inheritance works
- Configure the application differently for different profiles (like running Tomcat on a different port)
Add Spring Boot test slices for every layer
- Hints:
  - @DataJpaTest
  - @WebMvcTest
- Make sure to fail the test first before you fix it ;)
Testcontainers
- Introduce more advanced repository layer integration tests
- Replace H2
- introduce test containers to run repository integration tests against a real MySQL instance running in Docker
Introduce tests for the service layer
- What to choose? Unit tests (Mockito) or integration tests?
- If you choose to do integration tests make sure tests are not leaving traces behind in the database!
AssertJ
- Use this great library
- Rewrite your assertions
- Experiment with the fluent API try out to do assertions on collections
Cloud native buildpacks
- Build an OCI image for your Spring Boot application
- Without using a Docker file
- Add your Spring Boot Application OCI image to the docker-compose.yml
- Start your Spring Boot application from Docker docker-compose up -d (you need to shut down the application first from your IDEA or Maven plugin)
- Don't forget to configure the connection to the database because the application will not run inside a container ;)
- Small hint see datasource configuration in: application.yml
Archunit
- Enforce your architecture rules
- By creating some Archunit tests
- Examples:
  - Service layer should be called only by the Rest layer
  - Repository layer should only be called by the service layer
- Try to use some default archunit rules to enforce things like:
  - We don't use Jodatime in the project
  - We don't use the old Java data classes

Execute http calls to the rest API

IntelliJ http calls (Requires IntelliJ Ultimate)

You can also use curl:

Call the Spring Boot Info actuator

curl http://localhost:8080/actuator/info | jq

Call the Spring Boot Health actuator

curl http://localhost:8080/actuator/health | jq

Create a user

curl -XPOST  -d '{"userName":"Rod"}' -H "Content-Type: application/json" http://localhost:8080/api/users

Find a user

curl http://localhost:8080/api/users/1

Reference Documentation

For further reference, please consider the following sections:

j-tim / spring-boot-training-playground